I'm not that convinced, you've still got to get through mine fields, you've still got to clear trenches, that has to be done with dis-mounted infantry which is dangerous and takes time. Although modern western aircraft has a lot of advantages and if Ukraine had some it would make a big difference, Russia still has effective AA defences and air power isn't everything. Part of the problem with western media is there is an assumption that western equipment is all conquering and invincble, well it's mostly good but it's not that good, also there is an erroneous tendancy to underestimate Russian capability and portray their generals as being idiots. Ukraine is doing extreamly well in the circumstances against a powerfull well armed opponent, it's a very large theater of operations and even if they had air supremacy I doubt they could go much quicker, also Russia still has a LOT of artillary.